多結節状の形態を呈した胃平滑筋腫の1例

Multinodular Gastric Leiomyoma, Report of a Case

要旨　患者は44歳，女性．検診の胃X線検査で病変を指摘され，前医を受診した．胃内視鏡検査にて粘膜下腫瘍を指摘され，超音波内視鏡下穿刺術目的で当科を紹介された．胃X線および内視鏡検査にて，胃体上部後壁に径6cm大のブドウの房状の粘膜下腫瘍を認めた．超音波内視鏡検査では，胃壁第4層と連続性を有する均一な低エコー腫瘤として描出された．内視鏡的に病変周囲を切開し，その切開に沿って腹腔鏡下に腫瘍を切除した．切除標本の割面像において腫瘍は黄白色の大小様々な結節より成り，病理組織学的には粘膜下層を主体とした紡錘形細胞から成る多結節性の腫瘍であった．免疫組織化学染色ではα-SMAが陽性，c-KIT，CD34，S-100蛋白は陰性であった．以上より胃平滑筋腫と診断した．

　A 44-year-old woman presented with a gastric abnormality detected on upper GI series malignancy screening. She was referred to our hospital for endoscopic ultrasound-guided fine needle aspiration（EUS-FNA）of a gastric submucosal tumor. Upper GI series and EGD revealed a 6cm grape-shaped multinodular submucosal tumor, measuring 6cm in size, on the posterior wall of the upper gastric body. EUS revealed a homogenous hypoechoic mass connecting to the fourth layer of the gastric wall. Cytology obtained by EUS-FNA showed spindle-shaped cells. The tumor was resected by a novel method involving laparoscopic and endoscopic cooperative surgery（LECS）. Macroscopically, a cross-sectioned specimen of the tumor consisted of pale yellow multiple nodules. Histologically, the tumor was located mainly in the submucosa, and consisted of fascicles of spindle-shaped cells. The tumor was partially connected to the muscularis propria, but not to the muscularis mucosa. Immunohistochemically, tumor cells were positive for α-SMA and negative for KIT, CD34, and S-100 protein. The tumor was therefore diagnosed as a leiomyoma of the stomach.